Is hybrid fixation in revision TKA using LCCK prostheses reliable?

INTRODUCTION: The optimal technique for component fixation in revision total knee arthroplasty (rTKA) remains controversial: full cementation (FC) versus hybrid fixation (HF), which involves press-fit stem with cement fixation in the metaphyseal and epiphyseal zones. Previous series have either demonstrated the superiority of one or the other of these techniques or their equivalence. However, few studies have compared these 2 methods for rTKA using the Legacy® Constrained Condylar Knee (LCCK) prosthesis (Zimmer, Warsaw, Indiana, USA). HYPOTHESIS: Our hypothesis was that HF of LCCK components is associated with a higher rate of aseptic loosening (AL) than FC. MATERIALS AND METHODS: This was a single-center, multi-surgeon, retrospective study. Primary revisions between January 2010 and December 2014 were included for all indications. The only exclusion criterion was death without revision before the 5-year follow-up. The primary objective of this study was to compare the survivorship of 2 groups of LCCK components (femoral or tibial), depending on whether their stems had been cemented (HF versus FC), taking AL, revised or not, as the endpoint. The secondary objective was to look for other predictive factors of AL. RESULTS: A total of 75 rTKAs (150 components) were included. The FC group (51 components) had more Anderson Orthopedic Research Institute (AORI) type 2B and type 3 bone defects (BDs) (p<0.001), more reconstructions using trabecular metal (TM) cones (19 FCs and 5 HFs; p<0.001), and bone allografts (p<0.001). At more than 5 years, none of the FC components were loose compared to 10 HF components (9.4%), with 4 of these stems revised. The only significant difference was survivorship without radiographic AL at 9 years (FC=100%; HF=78.6%; p=0.04). The only predictive factor of AL in the HF group was the filling of the diaphyseal canal (p<0.01). The detrimental effect of BD severity (p=0.78) and the protective effect of TM cones were not demonstrated (p=0.21). DISCUSSION: Other series studying revisions using the same type of prosthesis also concluded the superiority of FC, not found for other revision prostheses. Despite this study's limitations (retrospective, multi-surgeon, limited sample size, and limited follow-up), all patient outcomes were known, and the difference in survivorship between the groups was very significant. CONCLUSION: HF has not been proven effective for the LCCK prosthesis. Better diaphyseal filling, wider metaphyseal bone tunnels enabling better cement injections, and stem designs more appropriate for press-fit fixation could improve these results. TM cones are an interesting avenue for further research. LEVEL OF EVIDENCE: III; retrospective comparative study.

Transplanted lungs and the "white plague": A case-report and review of the literature.

RATIONALE: Solid organ transplant recipients, especially after lung transplantation, are at increased risk for Mycobacterium tuberculosis pulmonary tuberculosis due to lifelong immunosuppression. PATIENT CONCERNS: A 41-year-old woman underwent a second bilateral lung transplantation that was complicated by fatal pulmonary tuberculosis. DIAGNOSES: Histological examination of a lung biopsy performed 6 weeks after retransplantation revealed a caseating granuloma and necrosis. Acid-fast bacilli were identified as rifampicin-susceptible M. tuberculosis by real-time polymerase chain reaction (PCR), confirmed by culture 2 weeks later. INTERVENTIONS: Our investigation led us to highly suspect that the transplanted lungs were the source of M. tuberculosis transmission. LESSONS: In order to optimize diagnosis and treatment for lung recipients with latent or active tuberculosis, regular assessment of lower respiratory samples for M. tuberculosis, particularly during the 12-month period posttransplant should be implemented. Regarding donor-derived transmission, screening donor grafts with latent tuberculosis by M. tuberculosis real-time PCR in lymphoid and adipose tissues is an option that should be considered.

Cerebrospinal fluid lens-free microscopy: a new tool for the laboratory diagnosis of meningitis.

Cerebrospinal fluid cytology is performed by operator-dependant light microscopy as part of the routine laboratory work-flow diagnosis of meningitis. We evaluated operator-independent lens-free microscopy numeration of erythrocytes and leukocytes for the cytological diagnosis of meningitis. In a first step, prospective optical microscopy counts of leukocytes done by five different operators yielded an overall 16.7% misclassification of 72 cerebrospinal fluid specimens in meningitis/non-meningitis categories using a 10 leukocyte/µL cut-off. In a second step, the lens-free microscopy algorithm adapted for counting cerebrospinal fluid cells and discriminating leukocytes from erythrocytes was modified step-by-step in the prospective analysis of 215 cerebrospinal fluid specimens. The definite algorithm yielded a 100% sensitivity and a 86% specificity compared to confirmed diagnostics. In a third step, a blind lens-free microscopic analysis of 116 cerebrospinal fluid specimens, including six cases of microbiology-confirmed infectious meningitis, yielded a 100% sensitivity and a 79% specificity. Adapted lens-free microscopy is thus emerging as an operator-independent technique for the rapid numeration of leukocytes and erythrocytes in cerebrospinal fluid. In particular, this technique is well suited to the rapid diagnosis of meningitis at point-of-care laboratories.